/*
 * Utilities for fetching data and images
 *
 * MIDP "Pico" Web Browser Framework
 *
 * (C) 2001 Beartronics Inc.
 * Author: Henry Minsky (h...@alum.mit.edu)
 *
 * Licensed under terms "Artistic License"
 *http://www.opensource.org/licenses/artistic-license.html
 *
 * $Id: HttpUtils.java,v 1.1 2007/01/07 16:52:37 daljeet_gandhi Exp $
 *
 */

package org.uni_hi.muus.util;

public class HTTPUtils {

	/*
	 * Decode a url-encoded string.
	 */

	public static String decodeURL( String str ) {
		StringBuffer result = new StringBuffer();
		int l = str.length();
		for ( int i = 0; i < l; ++i )
		{
			char c = str.charAt( i );
			if ( c == '%' && i + 2 < l )
			{
				char c1 = str.charAt( i + 1 );
				char c2 = str.charAt( i + 2 );
				if ( isHexit( c1 ) && isHexit( c2 ) )
				{
					result.append( (char) ( hexit( c1 ) * 16 + hexit( c2 ) ) );
					i += 2;
				}
				else
					result.append( c );
			}
			else
				result.append( c );
		}
		return result.toString();
	}

	private static  boolean isHexit( char c ) {
		String legalChars = "0123456789abcdefABCDEF";
		return ( legalChars.indexOf( c ) != -1 );
	}

	private static int hexit( char c ) {
		if ( c >= '0' && c <= '9' )
			return c - '0';
		if ( c >= 'a' && c <= 'f' )
			return c - 'a' + 10;
		if ( c >= 'A' && c <= 'F' )
			return c - 'A' + 10;
		return 0;       // shouldn't happen, we're guarded by isHexit()
	}

	final static String[] hex = {
		"%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07",
		"%08", "%09", "%0a", "%0b", "%0c", "%0d", "%0e", "%0f",
		"%10", "%11", "%12", "%13", "%14", "%15", "%16", "%17",
		"%18", "%19", "%1a", "%1b", "%1c", "%1d", "%1e", "%1f",
		"%20", "%21", "%22", "%23", "%24", "%25", "%26", "%27",
		"%28", "%29", "%2a", "%2b", "%2c", "%2d", "%2e", "%2f",
		"%30", "%31", "%32", "%33", "%34", "%35", "%36", "%37",
		"%38", "%39", "%3a", "%3b", "%3c", "%3d", "%3e", "%3f",
		"%40", "%41", "%42", "%43", "%44", "%45", "%46", "%47",
		"%48", "%49", "%4a", "%4b", "%4c", "%4d", "%4e", "%4f",
		"%50", "%51", "%52", "%53", "%54", "%55", "%56", "%57",
		"%58", "%59", "%5a", "%5b", "%5c", "%5d", "%5e", "%5f",
		"%60", "%61", "%62", "%63", "%64", "%65", "%66", "%67",
		"%68", "%69", "%6a", "%6b", "%6c", "%6d", "%6e", "%6f",
		"%70", "%71", "%72", "%73", "%74", "%75", "%76", "%77",
		"%78", "%79", "%7a", "%7b", "%7c", "%7d", "%7e", "%7f",
		"%80", "%81", "%82", "%83", "%84", "%85", "%86", "%87",
		"%88", "%89", "%8a", "%8b", "%8c", "%8d", "%8e", "%8f",
		"%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97",
		"%98", "%99", "%9a", "%9b", "%9c", "%9d", "%9e", "%9f",
		"%a0", "%a1", "%a2", "%a3", "%a4", "%a5", "%a6", "%a7",
		"%a8", "%a9", "%aa", "%ab", "%ac", "%ad", "%ae", "%af",
		"%b0", "%b1", "%b2", "%b3", "%b4", "%b5", "%b6", "%b7",
		"%b8", "%b9", "%ba", "%bb", "%bc", "%bd", "%be", "%bf",
		"%c0", "%c1", "%c2", "%c3", "%c4", "%c5", "%c6", "%c7",
		"%c8", "%c9", "%ca", "%cb", "%cc", "%cd", "%ce", "%cf",
		"%d0", "%d1", "%d2", "%d3", "%d4", "%d5", "%d6", "%d7",
		"%d8", "%d9", "%da", "%db", "%dc", "%dd", "%de", "%df",
		"%e0", "%e1", "%e2", "%e3", "%e4", "%e5", "%e6", "%e7",
		"%e8", "%e9", "%ea", "%eb", "%ec", "%ed", "%ee", "%ef",
		"%f0", "%f1", "%f2", "%f3", "%f4", "%f5", "%f6", "%f7",
		"%f8", "%f9", "%fa", "%fb", "%fc", "%fd", "%fe", "%ff"
	};

	/**
	 * Encode a string to the "x-www-form-urlencoded" form, enhanced
	 * with the UTF-8-in-URL proposal. This is what happens:
	 *
	 * <ul>
	 * <li><p>The ASCII characters 'a' through 'z', 'A' through 'Z',
	 *        and '0' through '9' remain the same.
	 *
	 * <li><p>The space character ' ' is converted into a plus sign '+'.
	 *
	 * <li><p>All other ASCII characters are converted into the
	 *        3-character string "%xy", where xy is
	 *        the two-digit hexadecimal representation of the character
	 *        code
	 *
	 * <li><p>All non-ASCII characters are encoded in two steps: first
	 *        to a sequence of 2 or 3 bytes, using the UTF-8 algorithm;
	 *        secondly each of these bytes is encoded as "%xx".
	 * </ul>
	 *
	 * @param s The string to be encoded
	 * @return The encoded string
	 */
	public static String encodeURL (String s)
	{
		StringBuffer sbuf = new StringBuffer();
		int len = s.length();
		for (int i = 0; i < len; i++) {
			int ch = s.charAt(i);
			if ('A' <= ch && ch <= 'Z') {               // 'A'..'Z'
				sbuf.append((char)ch);
			} else if ('a' <= ch && ch <= 'z') {        // 'a'..'z'
				sbuf.append((char)ch);
			} else if ('0' <= ch && ch <= '9') {        // '0'..'9'
				sbuf.append((char)ch);
			} else if (ch == ' ') {                   // space
				sbuf.append('+');
			} else if (ch <= 0x007f) {             // other ASCII
				sbuf.append(hex[ch]);
			} else if (ch <= 0x07FF) {             // non-ASCII <= 0x7FF
				sbuf.append(hex[0xc0 | (ch >> 6)]);
				sbuf.append(hex[0x80 | (ch & 0x3F)]);
			} else {                                  // 0x7FF < ch <= 0xFFFF
				sbuf.append(hex[0xe0 | (ch >> 12)]);
				sbuf.append(hex[0x80 | ((ch >> 6) & 0x3F)]);
				sbuf.append(hex[0x80 | (ch & 0x3F)]);
			}
		}
		return sbuf.toString();
	}

} 